Sulfur-graded kesterite structured film drives improvement of VOC

Siyu Wang; Yue Liu; Zhan Shen; Huamei Zhang; Li Wu; Juan Li; Fangyang Liu; Yi Zhang

doi:10.1063/5.0174239

Sulfur-graded kesterite structured film drives improvement of VOC

J Chem Phys. 2023 Oct 28;159(16):164703. doi: 10.1063/5.0174239.

Authors

Siyu Wang¹, Yue Liu¹, Zhan Shen¹, Huamei Zhang¹, Li Wu², Juan Li¹, Fangyang Liu³, Yi Zhang¹

Affiliations

¹ Institute of Photoelectronic Thin Film Devices and Technology and Tianjin Key Laboratory of Photoelectronic Thin Film Devices and Technology, Nankai University, Tianjin 300350, China.
² Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, School of Physics, Nankai University, Tianjin 300071, China.
³ Engineering Research Centre of Advanced Battery Materials (MOE), School of Metallurgy and Environment, Central South University, Changsha 410083, China.

PMID: 37873959
DOI: 10.1063/5.0174239

Abstract

Realizing the graded bandgap in absorber layer is very essential for high efficient thin film solar cells. However, such bandgap modification in kesterite-structured Cu2ZnSnSe4 is normally realized via high temperature sulfurization process (above 500°C), which is not only difficult to control the sulfurization depth, but also introduces additional deep defects because of the decomposition of absorber layer at such high temperature. In this study, a low-temperature sulfurization process (150°C) is developed. Such process not only inhibits the decomposition of Cu2ZnSnSe4 films and controls the elemental distribution very well, but also increase the surface bandgap of the absorber layer and form a gradient energy bandgap. Also, the density of deep-level defects in the Cu2ZnSnSe4 layer is reduced. As a consequence, the open circuit voltage of the solar cell is improved by 60 mV. This study paves the way towards the high efficient kesterite solar cell and other solar cells.